This invention is directed to sulfurized products prepared by the co-reaction of a sulfurized olefinic compound and a nitrogen-containing polymeric substance containing at least one free amine group, e.g., polyisobutenyl succinimide, which are useful as additives to lubricant compositions, various greases and normally liquid hydrocarbyl or hydrocarbyloxy fuels. This invention is particularly directed to a process of preparing these sulfurized products, the products so prepared and lubricating and fuel compositions containing them. The reaction products prepared in accordance with the invention are highly effective multifunctional antiwear additives which also provide surprisingly improved thermal and oxidative stability coupled with good frictional modifying characteristics.
Sulfurized olefins have been extensively used in many lubricant applications requiring extreme pressure/antiwear activity. These sulfurized olefins which include sulfurized C.sub.3-C.sub.8 olefins such as isobutylene are described by A. G. Horodysky in U.S. Pat. Nos. 3,703,504; 3,703,505; and 3,873,454. These patents and U.S. Pat. No. 4,240,958 generally employ methods of preparing their sulfurized products wherein the olefin is sulfohalogenated with a sulfur halide at some stage in their synthesis.
The direct sulfurization of olefins such as triisobutylene with sulfur is described, for example, in U.S. Pat. Nos. 2,995,569, 3,673,090 and 3,796,661. U.S. Pat. Nos. 3,345,380 and 2,535,706 describe methods of making various thiones by reacting elemental sulfur and unsaturated hydrocarbons.
The use of amine-containing polymeric succinimides has also found widespread use in both fuels and lubricants as dispersants and detergent additives. U.S. Pat. No. 3,600,327 teaches reacting sulfur with olefinic polymers and subsequently reacting the product thereof with primary, secondary or tertiary amines, disclosed mixtures of sulfurized additive products and soluble amines. U.S. Pat. No. 3,664,955 discloses reacting elemental sulfur with long chain olefinically unsaturated monomers C.sub.16 + or polymeric hydrocarbons such as polyisobutylene and using such compounds in conjunction with amine dispersants such as polyisobutenyl succinic anhydride condensed with tetraethylene pentamine. U.S. Pat. No. 3,390,086 discloses a reaction of polyalkylene succinimides with elemental sulfur and U.S. Pat. No. 3,401,118 discloses a preparation of alkenyl succinimides by reacting high molecular weight polyisobutenyl succinic anhydride with tetraethylene pentamine and thereafter reacting the product thereof with low molecular weight polyisobutenyl succinic anhydrides.
However, no prior art patent or publication or other reference known to applicants teaches the direct co-reaction of an olefin with elemental sulfur and the subsequent reaction of the product thereof with an amine-containing polymeric compound as disclosed herein.